3D printed guide template technique combined with multiple derotation for severe rigid scoliosis / 中国组织工程研究

BACKGROUND:In recent years,with the development of 3D printing,surgical surgery has become personalized and accurate.3D printed guide template technique can realize preoperative planning and intraoperative navigation,making surgery more accurate.In clinical orthopedic surgery for moderate and severe stiff scoliosis,there is still a problem that the accuracy of screw placement is not high,resulting in screw loosening and even nerve complications.There are few studies on 3D printed guide template technique to guide screw placement in surgery for severe stiff scoliosis. OBJECTIVE:To evaluate the clinical effect of the 3D printed guide template technique combined with multiple posterior derotation in the treatment of severe rigid scoliosis. METHODS:The clinical data of six patients with severe scoliosis undergoing 3D printed guide template technique of pedicle screw combined with multiple posterior derotation were retrospectively analyzed.There were 3 males and 3 females,with a mean age of(18.17±3.49)years(range,15-23 years).The changes of parameters related to lateral bending were analyzed at postoperative 2 weeks and 18 months,and the results were obtained by statistical analysis. RESULTS AND CONCLUSION:(1)The operation time was 280-540 minutes(mean 340.83±102.20 minutes).The intraoperative blood loss was 1 000-4 000 mL(mean 2 000.00±1 073.70 mL).The fixed segments were 9-14 vertebral bodies(mean 11.83±1.72),and no screw loosening occurred during the operation.(2)All patients were followed up.At postoperative 2 weeks,the anteroposterior and lateral radiography of the whole spine showed that the cobb angle,the distance between the vertical line of C7 on the coronal plane and the median line of S1,the distance between the vertical line of C7 in the sagittal plane and the posterior edge of S1,apical vertebral translation,thoracic kyphosis,and lumbar lordosis were significantly corrected.The average correction rate of the cobb angle in the main curve was 62.22%.After 18 months of follow-up,there was no significant change in all parameters compared with 2 weeks after operation;the orthopedic effect was satisfactory,and there was no infection or internal fixation fracture.(3)There was one case of delayed wound healing;scar healing appeared after dressing change treatment;no neurological complications occurred.(4)The results show that the 3D print-guide template combined with multiple posterior rod derotation technique is safe and effective in the treatment of severe rigid scoliosis,and the correction effect is satisfactory.

Three kinds of 3D printed models assisted in treatment of Robinson type Ⅱ B2 clavicle fracture / 中国组织工程研究

BACKGROUND:With the application and development of 3D printing technology in medicine,orthopedic internal fixation surgery has become precise and individualized.The equal-scale fracture model obtained by 3D printing technology was simulated and planned before surgery,realizing the leap from traditional 2D images to more vivid and detailed three-dimensional objects.It allows the surgeon to understand the fracture type in advance and rehearse the reduction sequence,so as to realize the individualized implementation of fracture surgery,optimize the surgical process,bring better postoperative recovery and less surgical complications. OBJECTIVE:To compare clinical efficacy of three 3D printed models combined with computerized virtual repositioning technology to assist incision reduction bone plate internal fixation and traditional incision reduction bone plate internal fixation in the treatment of Robinson II B2 clavicle fracture. METHODS:Eighty patients with Robinson II B2 clavicle fracture were randomly divided into trial group(n=40)and control group(n=40).In the trial group,three kinds of 3D printing models(affected clavicle fracture model,computer simulation clavicle fracture reduction model,clavicle mirror model of healthy side)combined with computer virtual reduction technology were used for preoperative in vitro surgery rehearsal.Finally,3D printing was used for clavicle mirror model of healthy side to advance bending and select bone plates for internal fixation.In the control group,open reduction plate internal fixation was applied.The time from admission to surgery,intraoperative blood loss,operation time,frequency of fluoroscopy,number of bends of the bone plate,fracture healing time,complications,and visual analog scale score and Constant score before and after surgery were compared between the two groups. RESULTS AND CONCLUSION:The time from admission to operation in the trial group was greater than that in the control group(P<0.05).Operation time,intraoperative fluoroscopy frequency and bending times of the bone plate in the trial group were lower than those in the control group(P<0.05).The trial group had faster fracture healing and fewer complications(P<0.05).There was no significant difference in intraoperative blood loss between the two groups(P>0.05).Constant score of the two groups had an increasing trend with time(F=613.50,P<0.001),but the difference between the groups was not statistically significant(F=0.08,P=0.78),and there was no interaction between the measurement times and the group assignment(F=0.27,P=0.66).The visual analog scale score decreased with time(F=1 149.55,P<0.001),but there was no significant difference between groups(F=0.02,P=0.88),and there was no interaction between the number of measurements and the group assignment(F=1.02,P=0.36).The results show that the use of 3D printed model combined with computer virtual reduction technology for preoperative rehearsal can shorten the operation time,reduce the number of intraoperative fluoroscopy frequency and the times of bone plate bending,and have the advantages of faster fracture healing,fewer complications,and similar functional recovery to the traditional incision reduction bone plate internal fixation.

Study on the evaluation of glenoid bone defects by MRI three-dimensional reconstruction / 中国修复重建外科杂志

OBJECTIVE@#To investigate the feasibility of MRI three-dimensional (3D) reconstruction model in quantifying glenoid bone defect by comparing with CT 3D reconstruction model measurement.@*METHODS@#Forty patients with shoulder anterior dislocation who met the selection criteria between December 2021 and December 2022 were admitted as study participants. There were 34 males and 6 females with an average age of 24.8 years (range, 19-32 years). The injury caused by sports injury in 29 cases and collision injury in 6 cases, and 5 cases had no obvious inducement. The time from injury to admission ranged from 4 to 72 months (mean, 28.5 months). CT and MRI were performed on the patients' shoulder joints, and a semi-automatic segmentation of the images was done with 3D slicer software to construct a glenoid model. The length of the glenoid bone defect was measured on the models by 2 physicians. The intra-group correlation coefficient ( ICC) was used to evaluate the consistency between the 2 physicians, and Bland-Altman plots were constructed to evaluate the consistency between the 2 methods.@*RESULTS@#The length of the glenoid bone defects measured on MRI 3D reconstruction model was (3.83±1.36) mm/4.00 (0.58, 6.13) mm for physician 1 and (3.91±1.20) mm/3.86 (1.39, 5.96) mm for physician 2. The length of the glenoid bone defects measured on CT 3D reconstruction model was (3.81±1.38) mm/3.80 (0.60, 6.02) mm for physician 1 and (3.99±1.19) mm/4.00 (1.68, 6.38) mm for physician 2. ICC and Bland-Altman plot analysis showed good consistency. The ICC between the 2 physicians based on MRI and CT 3D reconstruction model measurements were 0.73 [95% CI (0.54, 0.85)] and 0.80 [95% CI (0.65, 0.89)], respectively. The 95% CI of the difference between the two measurements of physicians 1 and 2 were (-0.46, 0.49) and (-0.68, 0.53), respectively.@*CONCLUSION@#The measurement of glenoid bone defect based on MRI 3D reconstruction model is consistent with that based on CT 3D reconstruction model. MRI can be used instead of CT to measure glenoid bone defects in clinic, and the soft tissue of shoulder joint can be observed comprehensively while reducing radiation.

Morphological classification and clinical significance of the coracoid process based on CT three-dimensional reconstruction / 解剖学报

Objective To provide anatomical basis for clinical treatment of acromioclavicular joint dislocation by studying the morphology of coracoid process of human scapula. Methods A total of 500 patients with shoulder injury were selected from the Affiliated Hospital of Traditional Chinese Medicine of Southwest Medical University in Sichuan Province, and 300 patients were selected as subjects, including 159 cases of right shoulder and 141 cases of left shoulder. CT scan images and 3D reconstruction results of scapula of the subjects were collected. The basic morphological characteristics of coracoid process CT images of the subjects were observed, and the relevant parameters were measured, including the longest horizontal distance of the coracoid process tip and the thickness of the midpoint (cd, pp’), the distance from the upper part of the coracoid process scapula to the base and the thickness of the midpoint (mn, kk’). The distance from the apex of the coracoid process to the base of the coracoid process (ab), the longest horizontal distance of the recursion part of the coracoid process (ef), the distance of as (point s was the intersection of point a perpendicular to mn), the distance of hj (point h and j were the intersection of the base of the coracoid process and the recursion part respectively), and ik (point i was the intersection of point k perpendicular to mn and the coracoid process retraction). Results According to the morphological characteristics of coracoid process, they were divided into five types, including peanut 29. 7%; Short rod type accounted for 27. 4%; Melon seed type accounted for 12. 6%; Rod type accounted for 17. 0%; Wedge type accounted for 13. 3%. Through data comparison, it was found that the distance ef and distance hj on the left were larger than those on the right, P<0. 05. All types had statistical difference in comparison distance cd, P<0. 05. The melon seed type showed statistical differences with peanut type, wedge type, long stick type and short stick type in thickness pp’, distance ab and as of point p, P<0. 05. In the comparison of point K thickness kk’, there was statistical difference between melon seed type and other four types, P<0. 05. In the distance ab comparison, there was statistical difference between the short bar type and the other four types, P < 0. 05. Conclusion The study on the morphology of coracoid process can provide anatomical basis for clinical reconstruction of coracoid ligament to treat acromioclavicular joint dislocation.

Anatomic classification of the sustentaculum tali and its characteristics analysis / 解剖学报

Objective To explore the anatomical morphology and characteristics of the sustentaculum tali based on CT three⁃dimensional reconstruction, so to provide anatomical support for the treatment of calcaneal fractures with screw implantation. Methods From March 2019 to March 2020, a total of 336 adult calcaneal CT three⁃dimensional reconstruction images from the Affiliated Hospital of Traditional Chinese Medicine of Southwest Medical University were collected after exclusion of inclusion criteria. The CT three⁃dimensional reconstruction of calcaneus was classified according to the β, the prolate axial intersection between sustentaculum tali and calcaneus on the normal posterior. Reference points, β; AB, the distance from the inside of sustentaculum tali to the inside of posterior talar articular surface; AC, the distance from the inside of sustentaculum tali to the outside of posterior talar articular surface; AD, the distance from the inside of sustentaculum tali to lateral of calcaneal; AE, the distance from the inside of sustentaculum tali to medial process of calcaneal tuberosity; AF, the distance from the inside of sustentaculum tali to calcaneal tuberosity; AG, the distance from the inside of sustentaculum tali to lateral process of calcaneal tuberosity. The results were statistically analyzed according to type, sex and body side. Results Under the β, the sustentaculum tali was classified into three types: typeⅠ(β<70°, 68 cases, 20.24%), type Ⅱ(70°≤β<80°, 153 cases, 45.54%), type Ⅲ(80°≤β<90°, 115 cases, 34.23%). For the distance of β, AB, AF, there were statistical differences between type Ⅲ and other types (P<0.05). For the distance of AE, there were statistical differences between type Ⅲ and typeⅠ(P<0.05). Meanwhile, for the distance of AB, AC, AD, AE, AF, AG, there were statistical differences between male and female (P<0.05). For the distance of β, AB, there were statistical differences between right and left (P<0.05). Conclusion Under the β, the sustentaculum tali is classified into three types, with the typeⅡas the main type. When treating calcaneal fractures with internal fixation, direction of screw implant can choose between 70° to 80° as soon as possible. The morphology and classification of sustentaculum tali are of certain clinical implication to treat calcaneal fractures.

Comparison of femoral tunnel and early curative effect analysis between arthroscopic three approach and traditional anteromedial portal for reconstruction of anterior cruciate ligament / 中国骨伤

OBJECTIVE@#To study the three-approach and traditional anterior medial technique to establish the femoral tunnel of position, length, and coronal angle and the early efficacy of anterior cruciate ligament reconstruction.@*METHODS@#Through retrospective research, from December 2018 to June 2019, a total of 36 patients diagnosed with simple anterior cruciate ligament tear and undergoing surgery were collected. All patients had a clear history of knee sprains and were divided into two groups. A group of 16 patients, including 11 males and 5 females, with an average age of (30.13±6.54) years and an injury time of 7 to 60 (30.19±15.78) days, three-approach technique was used to drill the femoral tunnel to reconstruct the anterior cruciate ligament. Another group of 20patients, including 15 males and 5 females, with an average age of (30.80±8.60) years, and an injury time of 7 to 60 (27.35±15.50) days, the traditional anterior medial approach was used to drill the femoral tunnel to reconstruct anterior cruciate ligament. CT 3D reconstruction technique was used to evaluate the femoral tunnel and the knee joint function was evaluated by Lysholm score of the knee joint.@*RESULTS@#All patients achieved primary healing after the surgical incision. No femoral tunnel fracture, vascular and nerve damage, difficulty in graft passage during the operation, and venous thrombosis occurred. All 36 patients were followed up on an outpatient basis, with a follow up period of 9 to 15 (12.00±2.83) months. Three-dimensional CT reconstruction was used to evaluate the femoral tunnel of the patients. The position of the femoral tunnel was described using the quartile method as the three-approach group:the lower (27.83±1.97) % of the femoral condyle and the posterior (25.57±3.20) %;the traditional approach group:the lower (28.38±3.21) % of the femoral condyle and the posterior (26.23±3.20) %. Bone tunnel length, three-approach group:(35.20±5.52) mm in total length, (23.20±2.07) mm in thick bone tunnel;traditional approach group:(34.60±4.26) mm in total length, (22.56±2.50) mm in thick bone tunnel. Coronal plane angle, three-approach group:(47.93±5.98) °;traditional approach group:(41.78±6.62) °. Knee joint Lysholm score, three-approach group:48.67±4.18 before surgery;97.00±2.48 at last follow up;traditional approach group:49.75±5.33 before surgery, 97.30±2.68 at last follow up, there were significant differences before and after surgery, no significant statistical difference between two groups.@*CONCLUSION@#The positions of the femoral tunnel drilled by the two methods were within the range of the anatomic stop of the anterior cruciate ligament, and there was no statistical difference. Compared with the traditional anterior medial approach, the coronal plane angle of the femoral tunnel drilled by the three-approach approach is relatively large, and there were no statistical differences in the length of the tunnel, the early postoperative effect of the two surgical methods, and the operation time. But the three approach has a wider and clearer vision. In addition, the knee flexion angle required for drilling the femoral tunnel during surgery is significantly smaller than that of traditional approach technology, which reduces the difficulty of surgery.

Value of PET/CT Combined with CT Three-dimensional Reconstruction in Distinguishing Different Pathological Subtypes of Early Lung Adenocarcinoma / 中国肺癌杂志

BACKGROUND@#The good prognosis of lepidic predominant invasive adenocarcinoma (LPA) and adenocarcinoma in situ (AIS)/microinvasive adenocarcinoma (MIA) in the pathological subtypes of early lung adenocarcinoma is similar, and the means to distinguish LPA from non-LPA is urgently needed in clinical practice. This study intends to analyze the correlation between positron emission computed tomography (PET)/computed tomography (CT) maximal standard uptake value (SUVmax) with CT three-dimensional reconstruction parameters and the pathological subtypes of early lung adenocarcinoma with part-solid nodules (PSNs) in preoperative imaging.@*METHODS@#The data of early lung adenocarcinoma patients who underwent anatomical pneumonectomy at the Department of Thoracic Surgery of Northern Jiangsu People's Hospital from January 2016 to January 2019 retrospectively analyzed and subsolid nodules on imaging were showed. All patients with enhanced chest CT and PET/CT data can be obtained completely, using Mimics software to perform three-dimensional reconstruction to obtain tumor volume, 3-dimensional mean-CT value (3Dm-CT) of tumor and SUVmax, using SPSS 25.0 for statistical analysis and GraphPad Prism 8.3.0 for drawing receiver operating curve (ROC). P0.7 were included in the multivariate ROC curve analysis, and the joint predictor (AUC=0.835) was obtained with medium or above predictive value.@*CONCLUSIONS@#PET/CT SUVmax and CT three-dimensional reconstruction parameters have a significant correlation with the different pathological subtypes of early lung adenocarcinoma with PSNs in imaging. The combination of SUVmax, tumor volume, ground glass component volume and 3Dm-CT of solid/ground glass component CT value has certain value in identifying the pathological subtype of early stage lung adenocarcinoma with PSNs nodules in imaging.

Application of three-dimensional reconstruction simulation to define the starting point of lumbar cortical bone trajectory / 中国修复重建外科杂志

Objective: CT three-dimensional reconstruction technology was used to simulate the placement of the lumbar cortical bone trajectory (CBT), to determine the starting point and direction of the screw trajectory. Methods: Between February 2017 and April 2018, 24 patients with lumbar CT were selected as the study object. There were 7 males and 17 females, with an average age of 50.4 years (range, 37-68 years). The CT DICOM data of patients were imported into Mimics 16.0 software, and the three-dimensional model of lumbar spine was established. A 5 mm diameter cylinder was set up to simulate the CBT by using Mimics 16.0 software. According to the different implant schemes, the study was divided into groups A, B, and C, the track of the screw respectively passed through the upper edge, the medial edge, and the lower edge of the isthmus of the pedicle. The intersection of simulated screw and lumbar spine was marked as region of interest (ROI) and a mask was generated. The average CT value [Hounsfield unit (HU)] and the screw length of ROI were automatically measured by Mimics 16.0 software. In addition, the head inclination angle and head camber angle of the screw were measured respectively. Point F was the intersection of the level of the lowest edge of the transverse process and the lumbar isthmus periphery. The horizontal and vertical distance between point F and the starting point were measured, and the relationship between the three schemes and the position of the zygapophysial joint and spinous process was observed. Results: Plan A has the highest ROI average HU, with the maximum value appearing in L 4; plan B has the longest screw length, with the maximum value appearing in L 5; plan C has the largest nail track head inclination angle, with the maximum value appearing in L 4; plan B has the largest nail track head camber angle, with the maximum value appearing in L 3. The screw length and head camber angle of the nail in group B were significantly greater than those in groups A and C ( P0.05). In plan A, 74.48% (143/192) screws had a horizontal distance of -2 to 4 mm from point F, a vertical distance of 6-14 mm from point F, a head inclination angle of (14.64±2.77)°, and a head camber angle of (6.55±2.09)°, respectively; in plan B, 84.58% (203/240) screws had a horizontal distance of 1-6 mm from point F, a vertical distance of 1-5 mm from point F, a head inclination angle of (26.93±2.21)°, and a head camber angle of (10.29±2.46)°, respectively; in plan C, 85.94% (165/192) screws had a horizontal distance of -2 to 3 mm from point F, a vertical distance of -2 to 4 mm from point F, a head inclination angle of (33.50±3.69)°, and a head camber angle of (6.47±2.48)°, respectively. Conclusion: Plan B should be selected as the starting point of the L 1-L 5 CBT implant. It is located at the intersection of the lowest horizontal line of the transverse process root and the lateral edge of the lumbar isthmus, which is 1-6 mm horizontally inward, 1-5 mm vertically upward, with a head inclination angle of (26.93±2.21)°, and a head camber angle of (10.29±2.46)°, respectively.

Applied anatomy research of the uncovertebral joint for design of uncovertebral joint fusion cage / 中国修复重建外科杂志

Objective: To measure anatomical parameters related to cervical uncovertebral joint and provide data support for the design of uncovertebral joint fusion cage. Methods: According to the inclusion and exclusion criteria, raw DICOM data of cervical CT scan in 60 patients (30 males and 30 females, aged 39-60 years) were obtained, then the three-dimensional cervical spine model was reconstructed for anatomical measurement by using the Mimics19.0 software. The height of the uncinate process, the length of the uncinate process, the width of the uncinate process, and the length of the uncovertebral joint in the intervertebral foramen region were measured bilaterally from C3 to C7. The anterior and posterior distances between the uncinate processes were measured from C3 to C7. The height of the uncovertebral joint space, the central height of the intervertebral disc space, and the depth of the intervertebral disc space were also measured from C2, 3 to C6, 7. The mean, standard deviation, maximum, and minimum were calculated by using the SPSS22.0 statistical software for the design of uncovertebral joint fusion cage. Results: The height of the uncinate process, the length of the uncinate process, the width of the uncinate process, and the length of the uncovertebral joint in the intervertebral foramen region of C3-C7 and the height of the uncovertebral joint space of C2, 3-C6, 7 showed no significant difference between two sides (P>0.05). The height of the uncovertebral joint space also had no significant difference between females and males (P>0.05). The anterior distances between the uncinate processes of C3-C7 were significantly larger than the posterior distances between the uncinate processes (P<0.05), the uncovertebral joint presented a posterior cohesive shape. The central height of the intervertebral disc space in male group was slightly higher than that in female group, and the differences were significant (P<0.05) at C2, 3 and C5, 6; the depth of the intervertebral disc space in male group was significantly higher than that in female group (P<0.05). The central height of the intervertebral disc space was (4.94±0.49) mm (range, 3.81-5.90 mm), the depth of the intervertebral disc space was (15.78±1.23) mm (range, 12.94-18.85 mm), the anterior and posterior distances between the uncinate processes were (17.19±2.39) mm (range, 13.39-24.63 mm) and (10.84±2.12) mm (range, 7.19-16.64 mm), respectively. According to the results of the anatomical research, the height of the uncovertebral joint fusion cage was designed as 5, 6, 7, and 8 mm; the depth of the uncovertebral joint fusion cage was designed as 12, 13, 14, 15, and 16 mm; the width of the uncovertebral joint fusion cage was designed as 14-18 mm; and the two wings are designed as arc-shape with 2 and 3 mm in width. Conclusion: There are certain differences in the anatomical parameters of the uncovertebral joint between different segments. The uncovertebral joint fusion cage that designed based on the results of anatomical research is suitable for most patients.

Classification and clinical significance of Chinese scapular spine based on CT three-dimensional reconstruction / 解剖学报

Objective: To explore the morphological classification and clinical significance of scapular spine based on CT three dimensional reconstruction. Methods: The scapular spines of 280 adults in the Affiliated Hospital of Traditional Chinese Medicine of Southwest Medical University were classified by CT plain scan and three-dimensional reconstruction, and its guiding significance for clinical work was discussed. Measurement content the distance between the seven structures of the scapular region and the thickness of the nine points. Results: Under the CT 3D reconstruction, the scapular spines were divided into five types: thin shape, wood rod shape, thick shape, fusiform shape and S shape. There were 14 cases of thin shape, accounting for 14.64%; and 63 cases of wood rod shape, accounting for 22.50%; and 78 cases of wood rod shape, accounting for 27.86%; and 89 cases of thick shape, accounting for 27.86%; and 89 cases of fusiform shape, accounting for 31.7p%, and 9 cases of S shape, accounting for 3.21%. In the thin shape, the thickness of B (9.36±3.61) mm was obviously thinner than the other four types (P<0.05); In thick shape, the length of AC (84.36± 6.00) mm and AD (84.36±6.00) mm was longer than the other four types, and the thickness of F, H, I, K was the thickest (P<0.05); In the fusiform shape, the length of BC was the shortest, and the thickness of K was the thinnest except for the thin shape (P<0.05). Conclusion: Under the CT 3D reconstruction, the scapular spines are divided into five types; thin shape, wood rod shape, thick shape, fusiform shape and S shape. Among them, fusiform shape is the most, and S shape is the least; The scapular spine of thick shape is the most abundant bone, which is the high quality source of autologous bone graft, and can also be used as a better fixed position for internal implants. On the contrary, the scapular spine of thin shape has the least amount of bone, and the internal fixation strength is relatively poor. Different types of scapular spines have certain effects on their operative method.

The Correlation of Normal Adult Mastoid Pneumatization Volume and the History of Otitis Media in Childhood / 听力学及言语疾病杂志

Objective To explore the volume size of mastoid pneumatization in normal adults and the relation‐ship with a history of recurrent otitis media in childhood .Methods A total of in 40 adults (80 ears) ,based on with or without otitis media in childhood ,were divided into the study group (n= 20) and the control group (n=20) . The volume sizes of mastoid pneumatization were measured by temporal bone CT scanning of three-dimensional re‐construction ,and the relationship with the history of childhood ear infections was studied .Results The average vol‐ume of pneumatization in all 80 temporal bones was 10 .4 ± 1 .8 ml .The average volume of pneumatization in sub‐jects without otitis media history (48 ears) and subjects with a history of otitis media (32 ears) were 9 .7 ± 2 .2 ml and 6 .3 ± 1 .7 ml ,respectively .The difference was statistically significant (P0 .05) .Conclusion The volumes of mastoid pneumatization in normal ears have a wide range .The subjects with a history of recurrent otitis media in childhood may be the cause of the volume decrease of mastoid pneumatization in adulthood .

Individual pedicle screws placement for correction of Lenke Ⅰscoliosis / 中国矫形外科杂志

0.05). However,the accuracy in placement pedicle screws and derotation rate of apical vertebrae were much higher in the individually treated group than those in the standard group (P=0.001,0.02).[Conclusion]The accuracy in placement pedicle screws and correction effects on transverse plane of patients with Lenke Ⅰ AIS can be improved significantly by individual selection of entrance point.